There is no physical difference in the two processors, there is a logical difference where the 2700k comes with a stock multiplier of 35 instead of the 2600k's 34. With both being unlocked 'k' processors you can simply go into your bios on a p67 or z68 motherboard and increase a 2600k's multiplier to match a 2700k.

In terms of overclocking the 2700ks aren't 'binned' or higher caliber than the 2600ks, it's still luck of the batch and you can get golden 2600k/2700ks and you can get poor 2600ks/2700ks.

So I would conclude that there is no difference between the two processors other than intel re-branding some 2600ks as something 'new' and 'faster'.